The invention relates to a dispensing assembly for automatically adjusting the carbon dioxide level in beer in a draught beer keg, the assembly being of the type stated in the introductory clause of claim 1.
Most draught beer dispensing assemblies are not provided with any type of automatic adjustment of the carbon dioxide level in the draught beer. The carbon dioxide level in the beer has for instance been manually adjusted by means of a valve and an associated manometer placed on the carbon dioxide compressed air cylinder. The carbon dioxide level in the beer is closely correlated with the beer temperature. When the carbon dioxide level is too high, the beer foams, and when the level is too low the beer turns flat. It is also known that a change of the draught beer keg requires a readjustment of the carbon dioxide level in order to prevent the beer from foaming or turning flat. Such a procedure is necessary because the new draught beer keg has a temperature differing from the temperature of the just emptied draught beer keg, typically because said draught beer kegs are not stored in the same room.
Previous attempts at solving this problem involved electric control systems comprising electric pressure and temperature sensors as well as electrically controlled valves. In a known assembly the carbon dioxide level is controlled by means of a valve with a secondary liquid, said valve not being directly connected to the beer keg. When beer is tapped from this dispensing assembly, the beer flows through the valve and transfers its temperature to the secondary liquid, which in turn acts on a valve seat opening and closing the feeding of carbon dioxide.
As the valve is not connected to the draught beer keg, said valve and said beer in the keg do not necessarily have the same temperature, which can cause an undesirable flow of carbon dioxide into the keg.
The known control system are rather comprehensive and rather complicated. In addition, they require a substantial adaptation when they are to be mounted on a new beer keg. Furthermore, the initial costs are relatively high.
FR-A-2490311 discloses a reducing valve to keep the CO2-concentration of beer constant at different temperatures. This reducing valve has a bellows device but this is not fixedly mounted in the housing of the valve. The bellows device contains glycerine, not a control gas mixture. Further nothing is mentioned about the reducing valve (formed as a needle/cone valve) being directly connected to a gas channel in the housing of the beer tap.
DE-A-3429299 discloses a beer engine comprising a CO2-cylinder, a primary and a secondary reducing valve, a draught beer keg, a beer tap on said keg and a tapping cock. The primary and the secondary reducing valves are not directly connected to a gas channel in the housing of the beer tap.
The object of the invention is to provide a dispensing assembly of the above type which presents a very simple structure, which is easy to adjust to an existing draught beer equipment, and which furthermore is inexpensive to buy.
The dispensing assembly according to the invention is characterised in the features stated in the characterising clauses of claim 1. As a result, a very high structural simplicity is obtained because it is utilized that the reducing valve and the beer in the beer keg always have the same temperature, an equalization of the temperature between the beer keg and the reducing valve taking place through the housing of the beer tap. Accordingly, no particular thermosensor is necessary in connection with the reducing valve. The control gas mixture of the bellows device has the effect that the reducing valve is opened just so much that the amount of carbon dioxide passing through the reducing valve ensures that the beer in the keg is provided with a desired carbon dioxide level of R (% by weight) within a temperature range preferably being 5 to 30xc2x0 C. The dispensing assembly requires almost no adaptation to the existing draught beer equipment because the reducing valve used is easy to connect to the existing beer tap. Accordingly the dispensing assembly is inexpensive to install.
The carbon dioxide level R (% by weight) of the beer may according to the invention be in the range of 0.48 to 0.57% by weight, especially 0.51 to 0.55% by weight, preferably approximately 0.53% by weight. The resulting dispensing assembly can be used for the most frequent types of beer; in Scandinavia the beer presents predominantly an R of approximately 0.53% by weight.
In addition to carbon dioxide, the control gas mixture may include Freon 134A or a gaseous hydrocarbon, such as butane, with the result that said assembly can be adapted to beer types with a rather differing carbon dioxide level (R).
Moreover, the carbon dioxide of the control gas mixture may according to the invention represent 10 to 30% by volume, preferably 12 to 25% by volume of the control gas mixture, which turned out to be particularly advantageous.
Furthermore, when R is approximately 0.53% by weight, the carbon dioxide of the control gas mixture may according to the invention represent approximately 15% by volume and Freon 134A may represent approximately 85% by volume. The resulting assembly is particularly suited for the types of beer typical in Denmark and the remaining Scandinavia.
Moreover, when R is approximately 0.60% by weight, the carbon dioxide level may according to the invention represent approximately 20% by volume, and the content of gaseous hydrocarbon may represent approximately 80% by volume, whereby the assembly is particularly suited for use in connection with dispensing of types of beer from the Southern Germany.
According to the invention the needle/cone valve may be shaped such that it can operate with both high and low carbon dioxide pressures because the cone is provided with a slightly convex appearance compared to a geometrical cone. As a result the needle/cone valve can, as mentioned above, operate at both high pressures, viz. at 60 to 80 bar, where it receives the carbon dioxide directly from the carbon dioxide compressed air cylinder, and at low pressures, viz. at 4 to 5 bar, provided a conventional reducing valve is mounted at said compressed air cylinder.
Furthermore, the bellows device may according to the invention comprise a cup of sheet material, where a metal sheet bellows is secured inside said cup in a sealing manner, preferably by way of welding, so as to provide a closed chamber for the control gas mixture between said cup and said bellows. As a result, the bellows device can always act on the needle/cone valve body in such a manner that no manual adjustment of the valve is required.
Finally, the metal sheet bellows may according to the invention be in form of a body of revolution with a central projection which is adapted to press the valve body in the needle/cone valve into an open position through a strut, said valve body, however, also being subjected to an oppositely acting force by a pressure spring arranged in the valve housing. The resulting embodiment turned out to be particularly advantageous.
It should be noted that the reducing valve, as well as the dispensing assembly, is completely free of electric installations and does not require any manual adjustment. As the reducing valve is not passed by beer, said reducing valve does not suffer from any risk of sanitary problems.